1. Field of the Invention
The present invention relates to the field of pre-engineered building systems, and more particularly, but not limited to, an improved standing seam roof assembly and components thereof.
2. Discussion of Prior Art
The pre-engineered building industry has developed into a multi-billion dollar segment of the building construction industry in the United States, and it has experienced an increasingly greater share of the construction industry budget throughout the world. The established method of erecting the roof of a pre-engineered building is to erect the primary structural members; attach the secondary structural members to the primary structural members; secure the appropriate bracing members; roll blanket-type insulation across the secondary structural members; dispose roof panel members over the insulation; and connect the roof panel members to each adjacently disposed roof panel member and to the secondary structural members.
Numerous types of roof assemblies have heretofore been proposed for a pre-engineered building in an effort to provide a watertight roof assembly, while at the same time enabling the roof assembly to expand and contract as changes in temperature are encountered. Typical of such a prior art roof assembly which has met with considerable success in recent years is the standing seam roof assembly. The panel members of the standing seam roof assembly are joined to each other along adjacent sides such that the sides are lapped together to form the standing seams. The panel members of the standing seam roof are secured to the secondary structural members by means of clips. The interconnection of the panel members of the standing seam roof lend stiffness and strength to the roof structure, while allowing the roof structure to expand and contract as a function of the coefficient of expansion of the materials of which the roof panels are made and the temperature cycles to which the roof panels are exposed.
The repeated action of expansion and contraction on the panel members of the roof assembly tends to weaken the panel-to-panel-to-lap joint and thus often causes panels to separate, structural failure and leaks in the roof assembly. The leaks are generally caused by the weakening of the fastening members and working or kneading of the sealant used at the joints. In many of the prior art roof assemblies, the sealant employed required adhesion, flexibility and water repellency. Further, the design of the joint was in many instances such that the pressure on the sealant varied greatly throughout the length of the side lap and end lap joints of the panels and resulted in uneven distribution of the sealant and voids in the joints which frequently led to leaks.
Many of the before-mentioned problems encountered in the prior art standing seam roof assemblies, such as structural failures and leaks, have been overcome by the improved standing seam metal floating roof assembly disclosed in copending U.S. patent application Ser. No. 425,477, filed Sept. 28, 1982 and now U.S. Pat. No. 4,497,151. The standing seam floating roof assembly of the before-mentioned copending patent application is formed of elongated metal panels, each of which is provided with a female member formed along one side portion of the panel and a male member formed along the opposed side portion of the panel such that adjacent panels are interlocked with the female and male members thereof to form the standing seam. A clip standing seam of the roof assembly and the secondary structure such that the upper portion of the clip is disposed between the male and female members of the panels forming a standing seam. The clip is further constructed so that relative motion between the clip and the metal panels is substantially prevented. To assist in the watertightness of the standing seam a resilient material is disposed in the upper portion of the standing seam between the female member and the male member.
Furthermore, pre-engineered roof systems are constructed of identical sheet metal panels that are laid end to end, as well as side by side as discussed above. This presents the problem of sealing these butt joints, especially at the "four corner" areas where four of the panels are adjacent. Various butt joining techniques have evolved in the prior art, all of which involve overlapping and selective notching to achieve a near fitting joint, and liberal application of mastic to effect the best seal possible under the design circumstances. Serious deficiencies have been encountered in all known prior art butt joints, such as water leaks, high costs, tooling complications, packaging, etc.
The insulation of a pre-engineered building presents another major problem in the construction of such buildings. My U.S. Pat. No. 4,361,993, entitled "Frameless Enclosure Assembly" issued Dec. 7, 1982, addresses this problem, as does my U.S. Pat. No. 4,329,823 entitled "Support Spacer Apparatus" issued May 18, 1982, address the problems incurred with maintaining full insulation integrity throughout the roof and wall systems of pre-engineered buildings and the like.
The problem incurred with maintaining structural stability under varying load conditions on present day pre-engineered roofs is addressed by my U.S. Pat. No. 4,524,554 entitled "Structural Bracing System" issued June 25, 1985. Purlins are long T-shaped or C-shaped members that are bolted to extend across the primary structure of a pre-engineered building. A roof assembly is constructed over the purlins and over the layered insulation battings and roofing panels attached to the tops of the purlins. Metal panel roofs supported by the underlying purlins must transfer load to the primary building structure through the purlins. This load will be both from live loads (ambient elements of nature, repairmen, temporarily stored roofing materials, etc.) and from dead lads (permanently installed air conditioners, etc.). It is in particular the live load conditions which alternately place building purlins in tensional and compressive stress.